Vegetable glue and process for making the same



Patented June 25, 1935 UNITED STATES VEGETABLE GLUE AND PROCESS FOR MAKING THE SAME Ellery H. Harvey, Highland Park, Ill., assignor to Perkins Glue Delaware Company, a corporation 01 .No Drawing. Application May 6,1935, Serial No. 20,109

I 12 Claims. (01. met-23.4)

This invention relates to improvements in vegetable glue and the process for making the same.

Vegetable glue prepared from starch, alkali and water for bonding wooden surfaces as de- 5 scribed in U. S. Reissue Patent No. 13,436, has been in common use for many years. Theseglues are commonly made commercially by bursting starch in caustic alkali solution.

The principal object of my invention is to. produce a glue and process for producing the. same which shall constitute an improvement particularly over such glues and processes for producing them as heretofore practisedf I have found that improvements in-vegetable l5 glue and the process for making it may be made by bursting the starch in the presence of an oxidizing agent such as a peroxide. The peroxide should be present at bursting or shortly thereafter. One effect of such treatment is that the resultant glue is less viscous or lighter-bodied with the same proportions of starch and water or the glue is equally thin with a relatively less quantity of water. One embodiment of glues of this type made in accordance with my invention is a quick-setting vegetable wood glue. Vegetable glues made in accordance with the heretofore known processes set more slowly than the wellknown animal glue. .Where vegetable glue has been used for this purpose it has been the practise to leave the work glued with such vegetable glue under pressure in clamps for from about 12 to 24 hours. Whereas with animal glue such as has been usually employed for such work the same may be removed from the clamps in about 3 hours or less. In the manufacture of furniture bent work such as ordinary sewing machine tops, curved chair backs and seats, etc. it is customary to glue together a plurality of relatively thin sheets of wood, and then immediately after the form or mold having two faces of the curvature desired which two faces are then clamped together with the articles therebetween. whereby the articles are given the curved or bent form desired. The articles are held in such form or clamps until the glue joining the wood layers has set sufiiciently so that when removed from the forms or clamps the articles will not materially change their shape thereafter. If the articles are removed from the forms or presses too soon'before the glue has acquired sufllcient set, the wood layers willtend to assume their normal flat shape so that the articles will no longer have the desired or proper bent form or shape.

55 Vegetable gluehas been little used for'such glue has been applied, place a few of these in a. 'p d u'fi 50 a to p p o the V S i YO the or three hours.

general bent work as it required so long for the glue to acquire the necessary set that a relatively large number of clamps 'or press forms were required to handle a days output. Ordinarily with I vegetable glue a sufficient number of forms or 5 presses have been required to hold simultaneously a whole days work. The veneered articlesare taken from the forms the next morning and the forms then used for that days work. The forms take, up a great deal of room and are somewhat 10 expensive. With animal glue the articles may be taken from'the forms in about'3 ,hpurs or less so that only about one quarter or less number of forms are required to handle a days Work as compareduwith the use of vegetable glue. Be- 15 cause of this dilference'in quick-setting quality between'animal glue and the vegetable glue heretofore used, manufacturers have-fon-the most part continued to use animal glue for general bent work in spite of thegreater cost of animal glue, because they did not wish to -go to the trouble and "expense of providing three or four times as many forms or presses and. correspondingly increae their factory space in order to use vegetable glue in this work. i I 25 I have produced vegetable glues which are less viscous or lighter-bodied with the same proportions of starch or water or conversely the resultant glue is equally thin with a'relatively less quantity of water. Specific embodiments of vegetable glue for bent work and of a glue suffie ciently fluent so that it may be applied with a hand brush are given below, although the invention is not restricted to .such specific embodiments:- V

(l) I have found that a quick-set vegetable wood glue may be made by restricting the amount of water and. acting chemicallyon the starch for example with barium peroxide as hereinafter resultant glue relative to the amount of water, so that sufficientwater is dried out of the glue and absorbed in the wood to which it is applied in two Thereupon the glue has suflicient set to permit the bent veneered articles to be takenfrom the press without material detriment. I find that if the vegetable glue contains over Zparts of water to 1 part ofstarch byweight, it takes so long for the excess water ,to dry-out through the wood that the desired quick-setting 50 action is not obtai ned. 1 preferably use about 1 parts of water to 1 of starch. :Alsoif the viscosityof the resulting glue is too great, the glue will notpenetratethe wood poresproperly to obtain a firm rootage to obtain the necessary joint v '64 F. and true viscosity may be defined as the a force required to slide two solid surfaces, with the material the viscosity of which is being measured, therebetween, and which surfaces are one centimeter square and one centimeter apart, past one another with a velocity of one centimeter per second, (see U. S. Patent 1,236,706). For the purpose of measuring such viscosity I prefer to use an instrument and method such as that disclosed 'inU. S. Patent 1,236,706 granted August 14', 1917. This instrument and method are adapted to measure viscosity in centipoises, a centipoise being the force in-dynes required to slide two solid and smooth parallel surfaces with water therebetween, whichsurfaces are one centimeter square and one centimeter apart, past one another with a velocity of one centimeter per second, the water being at a temperature of 64 F. When measured at 90F.

'onthis instrument the glue is less than 150,000

times as viscousas water at 64 F. measured on the same instrument.

The specific procedure for producing this quick-set vegetable glue followsz-I took 100 pounds of cassava starch known as Galoehan and mixed with this 1% pounds of finely powdered barium peroxide (BaO) the mixture being thoroughly made and in the dry form. I then added this mixture to a suitable kettle containing 150 pounds of water, and agitated the same with a power driven mechanical agitator until the same was thoroughly mixed with the water and themixture free of lumps. I then heated the batch by means of a steam jacket to 160 F. and while continually stirring the mixture, added I slowly 3 pounds of caustic soda (actual NaOH) in the formof a solution of about 33% strengthto burst; the starch. By' bursting apparently the covering of the starch particles is broken and the interior material then is acted upon by the other ingredients present to form the colloidal semicool with continued agitation, when it was ready bent sewing machinetops, curved chair backs fiuid'glue. With the temperature continued at 160 F. the stirring was continued until the batch was transformed into a colloidal and semi-fluid but viscous glue. The glue was then allowed to for use in the well-known manner, having a viscosity substantially below 150,000 when measured asabove described. The glue was readily spreadable'by thecommon vegetable gluespreading ma- I chinery andhad substantially the cohesiveness and adhesi'veness of a good grade'of animal glue such as commonly used in furniture veneering. The glue also hasthe advantage that it may be applied cold and makes joints which are more permanent than those made with animal glue and which are less affected by extreme changes in humidity and temperature conditions. The glue had the characteristic property thatit was capable of joiningwood layers or veneers for the'common and seats, etc. with a setting actionv which permitted the workto be removed-from: the forms orpresses in less than 3 hours without the work materially changing its shape thereafter.

Instead of using heat during the mixing and solution of the starch to form the glue, the same may be carried out in the cold, i. e. at normal temperatures, but in such case the amount of caustic soda used should be increased from 3% to from 6% to and a longer time for making the glue is required. Other solvents maybe substituted for the caustic soda but I prefer this as it appears to have a slight degenerating action on the starch as well as the solvent action.

' (2) For a brush glue, I took one brand of cassava starch known as KTH brand and mixed it with 2 times its Weight of water and heated the batch to 160 F. which is about or just below the bursting temperature of the starch in water alone. To the mixture so heated I added, during continual agitation 12.5% of hydrogen peroxide (H202) and 3% of caustic soda, based on the weight of the starch. The hydrogen peroxide used was what is known as U. S. P. 10 volume hy-' drogen peroxide. The agitation was continued until the batch passed over from a mixture of suspended starch into a relatively fluid glue, having a specific viscosity at 160 F. of 1425 and it was then allowed to cool to 75 F. when it had a specific viscosity of 6975 and was ready for use. Thecaustic alkali is preferably added slowly in the form of a solution in a small amount of water. I find that the conversion with the caustic in the presence of the hydrogen peroxide produces a much less viscous glue than if the starch were converted with the caustic alone. The glue was sufiiciently fluid to be applied with a brush and produced joints between wood surfaces having substantially the strength of. animal glue joints.

(3) In another case I took 400 parts of another agitation parts by weight of 62% barium peroxide (33.02), the commercial barium peroxide containing some impurities such as barium oxide and barium carbonate. I then added 40 parts by weight of a 10% solution of hydrochloric acid and stirred the mixture for 5 minutes. I then added 3% of caustic soda based on the weight of the starch and heated the batch to 160 F. and continued the agitation until the mass was converted into a relatively fluid'glue having a specific viscosity of 675 at 160 F. I then permitted the glue to cool down to 75 F. when it had a specific viscosity of 5250 and was ready for use. The barium peroxide and hydrochloric acid seemed to affect the viscosity of the resultant glue in much the same manner as the hydrogen peroxide in the previousexample.

(4) In a similar manner I took another cassava starch known as Royal brand and converted it in 2%; parts of Water with 15% hydrogen peroxide, 3% of caustic soda and heat to 160 F. The resulting glue had a specific viscosity of 325 at 160 F. and when cooled down to 75 F. it had a specific viscosity of 3000. g a

(5) I also took another cassava starch and in a similar manner converted it into glue in 2%; parts of water with 1.75% of 89% barium peroxide and 3% caustic soda with heat to 160 F. and obtained a very satisfactory brush glue which when cooled to 75 F.'had a specific viscosity of 5475. .I have also used calcium peroxide in place of the barium peroxide with similar results.

(6) I also took some slightly degeneratedcas sava starch and similarly converted it in the same amount of water with 2% of chloride of lime, 4% of sodium bicarbonate and 3% caustic soda with l is present.

applied with a bristle brush although in some cases a wire brush'is preferable. The caustic .al-' kali is preferably added slowly in the form of a solution in a small amount of water.

The starchy materials may also be similarly converted into these brush glues without using heat but'in such case about 7% or more of the caustic is used to convert the glue. This makes the resulting glue quite alkaline and such alkalinity is likely to affect the brushes or the hands of the workmen. To overcome this the glue may be neutralized with acid but it is preferred to reduce the amount of caustic used to about 3% and convert with heat, and the resulting slight alkalinity of the glue is not a serious disadvantage. The caustic may thus be substituted largely, possibly entirely,by'the action of heat. The resulting glue should preferably contain not more than about 3 parts of waterto 1 of starch in order to avoid undue delay in drying and setting with possible warping of the wood and weakening of the joints.

The glues produced by some of the above mentioned examples for brush glues show a tendency to become somewhat lardy, especially on standing after conversion, but this is not serious so long as brushability is still retained and the lardiness is not so pronounced as to materially afiect the strengthoi joints made with the glue.

Other chemical reagents may be substituted for the barium peroxide in carrying out the inven tion, particularly other peroxides such as hydrogen peroxide, and with some starches the peroxides may be omitted altogether, provided some other chemical reagent giving the desired result The amounts of peroxide and water used may be varied somewhat and indeed should be varied somewhat in order to get the best results with different starches, which vary considerably as they come on the market, even in the same brand. i

In making glues-according to my invention the peroxide or like agent should be present to act at the time of bursting or shortly thereafter. Instead of adding the hydrogen peroxide or barium peroxide or other peroxide before or simultaneously with the addition of the caustic soda, the peroxide may be added to a partially or fully converted batch to get the required or desired reduction in viscosity or increase in fluidity. Likewise the peroxide may be added to the starch gelatinized in the water with heat, followed by the addition of the caustic alkali. Also the peroxide may be mixed with the starch before the latter is suspended in the water, but if hydrogen peroxide is used, the starch should be mixed with the water and converted without undue delay because if the mixture of starch and hydrogen peroxide is permitted to stand for any considerable length of time more or less of the hydrogen peroxide may evaporate and so prevent the desired result from being attained.

It may be pointed out that with glues made in accordance with this invention the viscosities vary inversely with the water content. In other words, of two glues made under identical conditions, except for the proportions of water employed therein, the one which has a substantially lower water content will have a substantially higher viscosity and vice versa. i

This application is a continuation in part of my copending applications Ser. Nos. 589,549 and 589,550, each filed September 21, 1922, and my copending application Ser. No. 615,151, filed January 26, 1923. Certain specific examples for glues appearing in said applications Ser. Nos. 589,549+50, whi h examples are considered to be within the scope of the claims appearing in the present application have been omitted from the latter for the sake of brevity. Accordingly applicant does not abandon the subject matter ofthese omitted examples, relating to glues, but asserts full right thereto. I

Many other changes and modifications may be made and various other chemicals substituted. Indeed, since the starches as they come on'the market vary widely in various qualities the per centages of chemicals used and the length and conditions of treatment will be varied with difi,

ferent starches in order to get the best results, but the above examples and explanation will enable those skilled in the art to obtain satisfactory results with many commercial starches. f WhatI claim is: a

l. The improved method of making cassava starch glue which has a water content of more, than 1 to about 3 parts of water to 1 part of starch and which is sufficiently fluent so that it may be readily flowed through pipes at ordinary temper atures, has a viscosity range of about 3000 to a viscosity of a wood glue applicable by machinery,"

and still has sufficient adhesiveness for joining wood, which comprises treating bursted cassava o starch at bursting or shortly thereafter with a peroxide in the presence 01"- about said proportion of water to reduce the viscosity of the resultant adhesive and forming a solution of the starch so treated.

2. The improved method of making cassava it may be readily flowed through pipes at ordinary temperatures, has a viscosity range of about 3000 toa viscosity of a wood glue applicable by machinery, and still has sufficient adhesiveness for joiningwood, which comprises bursting cassava starch in about said proportion of water in the presence of an alkaline reagent, treating the bursted starch at bursting or shortly thereafter with a peroxide to reduce the viscosity of the resultant adhesive, and forming a solution of the starch so treated.

3. The improved method of making cassava starch glue which has a water content of more than 1 to about 3 parts of water to 1 part of starch and which is sufficiently fluent so that it may be readily flowed through pipes at ordinary temperatures, has a viscosity range of about 3000 to a viscosity of a wood glue applicable by machinery, and still has sufiicient adhesiveness for joining'wood, which comprises heating and bursting the cassava starch'in about said proportion of water in'the presence of a caustic alkali, treating the bursted starch at bursting or shortly thereafter with a peroxide to reduce the viscosity of the resultant adhesive, and forming a solution of the starch so treated.

4. The improved method of making cassava starch glue which has a Water content of more than 1 to about 3 'parts of water to 1' part of starch and which is suificiently fluent so'that it may be readily flowed through pipes at ordinary temperatures, has a viscosity range of about 3000 to a viscosity of a wood glue applicable by machinery, and still has sufficient adhesiveness for joining wood, which comprises heating and bursting cassava starch in about said proportion of water in the presence of a caustic alka1i, treating peratures, has a viscosity range of about 3000t a viscosity of a wood glue applicable by machinery or brush, and still has sufficient adhesiveness for joining wood, which comprises bursting cassava starch in about said proportion of water by caustic soda and heat, treating the mass at bursting or shortly thereafter with a peroxide and forming with said water a solution of the starchso treated suitable for applying by machinery or brush.

6. A quick-setting vegetable glue containing products of reaction of cassava starch bursted in the presence of a peroxide such as an alkaline peroxide, caustic alkali and water, the water being present in the proportion by weight of less than 2 parts, of water to 1 part of starch, theglue having a viscosity of 150,000 or less, spreadable by the ordinary spreading machinery for vegetable wood glues, andcapable of joining wood layers and veneers in general bent work.

' '7. A quick-setting vegetable glue containing products of reaction of cassava starch bursted in the presence of an alkaline earth peroxidacaustic alkali and water, the water being present in the proportion by weight of less than 2 parts of water to 1 part of starch, the glue having a viscosity of 150,000 or less, spreadable by the ordinary spreading machinery for vegetable wood glues, and. capable of joining wood layers and veneers in general bent work.

8. A quick-setting vegetable glue containing products of reaction of cassava starch bursted in the presence of barium peroxide, caustic alkali and water, the water being present in the proportion by weight of less than 2 parts of water to l part of starch, the glue having a viscosity of 150,000 orless, spreadable by the ordinary spreading machinery for vegetable wood glues, and capable of joining wood layers and veneers in gen- 150,000 or less, spreadable by the ordinary spread ing machinery for vegetable wood glues, and capable of joining wood layers and veneers in general bent work. p

10. A vegetable glue comprising a solution of the reaction products of cassava starch bursted in the presence of a peroxide, alkal and water, the specific viscosity of the glue solution at 75 F. being about 15,000 or less, the amount of water in the glue being about 3 parts or less to 1 part of starch by weight, and the glue having substantially the adhesiveness of animal glue for joining wood.

11. A vegetable glue comprising a solution of the reaction products of cassava starch bursted,

in water in the presence of a peroxide, the viscosity of the glue solution at 75 F. being less than 15,000, the amount of water in the glue being about 3 parts or less to 1 part of starch by weight, and the glue having substantially the adhesiveness of animal glue for'joining wood.

12. A vegetable glue. comprising a solution of the reaction products of cassava starch bursted in the presence of a peroxide, alkali and water, the specific viscosity of the glue solution at 75 F. being less than 10,000, the amount of water in the glue being about 3 parts or less to 1 part of starch by weight, and the glue having substantially the adhesiveness of animal glue for joining wood. 7

ELLERY H. HARVEY. 

